In a digital radiography setup, why is it poor practice to rely on image brightness alone to judge exposure when exposure indicators are missing?

• A. Rescaling will not completed accurately if exposure indicators are unknown
• B. Histogram analysis cannot be performed without information related to exposure indicators
• C. Image contrast is determined based on the amount of radiation received by the image receptor
• D. Brightness does not reflect the amount of radiation the image receptor received

Answer: (D)

In digital radiography, what you see as brightness on the monitor is a result of post-processing decisions (window level/width and LUT mapping) applied after the image is captured. These adjustments can make an image look bright or dark without changing how much radiation actually hit the detector. So brightness is not a direct measure of receptor exposure. Exposure indicators provide a numeric, standardized indication of the detector dose, letting you judge whether the technique was appropriate. Without those indicators, judging exposure based on how bright the image looks can be misleading, because two images with the same brightness could have come from very different actual exposures.